1. Field of the Invention
The invention relates to multichannel programmable band comparators for apparatus used in cardiac surgery. During open heart surgery it is necessary to substitute for the cardiocirculatory and respiratory functions of the patient for a certain period of time using artificial apparatus. If such complex cardiac surgery, on which the life of a patient depends, is to have a successful outcome, the complex "machine" which is to substitute for the heart and lungs must operate correctly by reproducing conditions which are as similar as possible to actual physiological conditions. It is therefore equally vital to maintain under constant control delicate parameters such as blood flow, arterial and venal pressure, body temperature and acid-base equilibrium.
2. Description of the Prior Art
These functions have up to now been directly controlled by the medical and paramedical staff responsible for this area by means of the observation of a certain number of instruments which check that the values of the various parameters in question do not diverge from optimum values.
Instruments designed to carry out this monitoring function are not at present available. Consequently there is a need for a single instrument which is able to ensure that a certain number of parameters (up to eight) remain within their assigned field of variation by warning the medical personnel, by means of acoustic or visual signals, if one or more functions is in an abnormal situation.